The popularity of electro-mobility is growing rapidly worldwide, as well as in Latvia – the public is becoming better informed, both private and shared electric cars are becoming more common on the roads, and the number of charging stations has also increased. Unlike conventional combustion engine cars and their refuelling process, charging an electric car and the issues involved may seem complicated, but once you understand the charging process, everything will be just as simple and, unlike combustion engine cars, you can charge your electric car either slower or faster almost anywhere if an electrical outlet is available.

How is an electric vehicle charged?

When charging an electric car, you need to know the difference between two types of electric current – alternating current (AC) and direct current (DC). The household electricity grid is alternating current, while many electrical appliances use direct current to operate. The battery of an electric car is also charged with the use of direct current.

• In the event of AC charging, the conversion of current from alternating current to direct current takes place in the charging device built into the electric car. This process happens automatically when you plug in the AC charging plug of the electric vehicle. The charging speed of electric vehicles is affected by the power of the electricity connection of the charging device, as well as by the capacity of the onboard charger of the particular electric vehicle. This should be taken into account when selecting the AC charger to suit the needs of the purchased electric vehicle. AC charging is the most common type of charging.
• In the event of DC charging, the conversion of alternating current into direct current does not occur in the charging unit of the electric vehicle, as the charging station itself acts as a power converter. The charging speed at DC charging stations exceeds the speed in the event of AC charging several times, namely, the charging speed is no longer limited by the capacity of the onboard charger; however, manufacturers also set the maximum DC capacity for each electric vehicle, and furthermore, the charging power is not linear – it is affected by the battery temperature and other technical parameters.

What are the types of charging stations?

Charging stations are most often classified by their type of current – AC or DC. Meanwhile, the charging speed is basically characterised by the power available at the charging station, which can be used to charge the battery of the electric vehicle; however, the charging time not only depends on the power available at the station but also on the battery capacity, as well as other factors, which we will take a look at later.

• Level 1 – slow charging (1.8 to 3.6 kW) | AC

A standard Schuko 230 V socket with power of up to 3.6 kW and a nominal amperage of up to 16 A is available in every home. To ensure the safe charging of electric vehicles from such sockets, it is important not to exceed the technical parameters of the socket, which can overload the grid and cause a risk of fire. This is why manufacturers include a special charging device (EVSE) in their electric vehicles to ensure that the power of charging is not exceeded. Common current strength values for EVSE equipment are 8 A, 10 A and 12 A, which correspond to 1.8 kW, 2.3 kW and 2.7 kW of power respectively.

This type of charging is suitable for charging electric vehicles at night or in places where they are left for long periods of time. Charging speeds are 10–15 km per hour and, depending on the battery capacity, charging can take from 6 to even more than 48 hours. Most electric car owners only use this type of charging as a back-up option if no other charging options are available.

• Level 2 – fast charging (3.6 to 22 kW) | AC

Electric cars are most often charged using a special charging device that is usually attached to the wall of a building or garage, or to a pole. This charging device allows you to charge your electric vehicle several times faster, adjust the charging power to the power of the electric grid connection, keep track of the electricity used, program charging to take place at night, etc. Unlike a Schuko230 V socket, setting up this charging solution requires a certified electrician.

The charging device will ensure the option of charging a full electric vehicle battery in 3 to 8 hours or more, depending on the available charging power and the capacity of your electric vehicle’s battery. This special charging equipment can be installed at home, at the workplace, at supermarkets, hotels, etc., and is also the most common type of charging equipment at public charging stations.

• Level 3 – ultra-fast charging (from 20 to 350+ kW) | DC

Ultra-fast charging is characterised by the use of direct current for charging from the start. This type of charging station is the fastest charging solution currently available, and, depending on the technical parameters of the electric vehicle, can charge to a mileage equivalent to 100 km within 5 to 20 minutes.

Principally, this equipment is used at public charging stations located in places where drivers stop for a short time, for instance, on motorways, motorway junctions, etc. However, this type of charging station is also being set up in supermarkets, entertainment centres and other public places. They are also often used by users of electric vehicles who have limited charging options at home or at work.

What are the types of ports used in charging devices?

Unlike the usual household socket and standardised fuel nozzle, different electric vehicles have various types of connections or standards, which are mainly related to the country of origin of the vehicle manufacturer. In Europe, the main standards are Type 2 (for AC charging) and CCS2 (for DC charging). Type 2, CCS2 and CHAdeMO connection standards are available at public charging stations in Latvia, including e-mobi and Elektrum Drive stations. Users of other standards should consider the fact that they may need to purchase transistors.

• Type 1 – a connection standard for AC charging, it is common for electric vehicles manufactured in Asian countries and North America. Especially designed for first-generation electric cars. Some European manufacturers use a Type 1 plug in their US models.
• Type 2 – a connection standard for AC charging officially approved by the European Union in its territory. As global sales of electric vehicles develop, the second-generation Nissan Leaf, for example, is delivered in Europe with a Type 2 plug, while in the US it comes with a Type 1 plug.
• ChaDeMo – a DC charging standard that is mostly typical for electric vehicles of Asian manufacturers, and, initially, for some models made in Europe.
• CCS1 (or Combo 1) – the DC charging standard used in America, Korea and Taiwan. It is a single plug that combines CCS and Type 1 plugs. This should be taken into account when purchasing, for instance, electric vehicles imported from the US, as the European CCS charging plug will not be adequate and will have to be rebuilt.
• CCS2 (or Combo 2) – a DC charging standard officially approved by the European Union in its territory. It is a single plug that combines CCS and Type 2 plugs.
• Tesla cars use a variety of charging standards and plug types, including variations in different regions. For cars from this manufacturer, you may need to purchase appropriate charging adaptors to connect to another charging device.

What factors can affect the speed of electric vehicle charging?

Several factors affect the charging speed – they include the power available at the station, the electric vehicle’s built-in charging device, the battery cooling system, and even the selected driving mode and the outdoor air temperature. All factors are interrelated and will affect the charging speed of an electric vehicle.

• AC charging – the available power at the charging station and the power of the onboard charger of the electric vehicle. Electric vehicles often come with a standard 6–7 kW charger (this can be increased by ordering optional packages). If such an electric vehicle is connected to an 11 kW or 22 kW AC charger, the charging speed is equivalent to that of a 6–7 kW unit, regardless of the fact that higher power is available at the station.
• DC charging – each electric car manufacturer has set a maximum DC power that the car can take. If the maximum specified DC power of an electric car is 100 kW, then even at a 150 kW charging station, it will not exceed the 100 kW limit. It should be noted that the maximum DC charging capacity will also be affected by the temperature of the battery, both before and during charging. Note that DC charging is not linear; therefore, to extend battery life, maximum charging power is only available within the range of the battery specified by the manufacturer, for instance, from 10% to 75%.
• Battery cooling system – Different electric car models have different technical solutions for the charging process that aim to protect the battery from overheating. Increased battery temperature is reduced not only by the distance travelled but also by the charging speed. When buying an electric vehicle, it is important to pay attention to what type of battery cooling system it is equipped with – they are divided into passive and active. In the event of passive cooling, the battery elements are cooled by the supplied airflow; this design is cheaper and less efficient. Active cooling is implemented with the help of a liquid circulation system – such systems ensure a more even battery temperature and are more efficient but more expensive.
• Driving mode and outdoor temperature – if an electric vehicle equipped with a passive battery cooling system has been driven actively for a long time on the highway or in high outdoor air temperatures, the charging process may be slower than under identical conditions with an active cooling system. In some cases, where the battery temperature is too high or too low, the electric car system will not allow you to use the full power available; it will first heat or cool the battery, and only when the optimum parameters are reached will it be able to use the maximum power available for charging according to the technical settings.

Elektrum Drive, by developing the infrastructure of the electric vehicle charging network, will take care to ensure that it is possible to charge your car conveniently, quickly, in an up-to-date way and with green, environmentally friendly energy at your home, as well as on the road.